VDOS "initial findings"

[Sean McNamara <sean@macassist.com.au>]

Hi there,

posted last week about a DOS I found on one of my old disks - VDOS, by 
Vincent Tan. I have found no references to it on the 'net, in the FAQs, 
etc.

The version of VDOS I have is v1.6, written in 1984. I did some snooping 
with Byte Zap, and found a list of commands:

VDOS
LOAD
SAVE
RUN
/
DELETE
LOCK
UNLOCK
CLOSE
READ
EXEC
WRITE
POSITION
OPEN
APPEND
RENAME
CATALOG
MON
NOMON
PR#
IN#
MAXFILES
AL
UNDELETE
FP
INT
BSAVE
BLOAD
BRUN
VERIFY
TDUMP

I've discovered that VDOS, which drops to monitor, is just the prefix 
for two other commands - VDOSI (VDOS' initialisation routines) and VDOSC 
(VDOS' copy routines). / is a shorthand version of CATALOG. AL just 
gives binary address and length numbers (last load/save?).

TDUMP does a text dump - but with the minimal playing I've done with it 
so far, have only gotten it to dump 1 character! I haven't tried the 
UNDELETE function yet - VERIFY I've only tried on files I know to be 
good, and it's not come up with a message. I know there's a corrupt file 
on the original disk I got VDOS from, but that file prevented me from 
making a disk image for me to play with, and I haven't had the //e set 
up since.

The VDOSI initialising routines load VDOS into memory and then dump them 
onto a new disk with an optional disk format.

VDOSC allows you to specify source and target slot/disk, and start and 
end sectors.

I sent Willi Kusche (on request) a disk image with VDOS on it, and his 
initial observations were:

>    It seems that the sectors that make up VDOS are stored
> in the boot area in a different order than DOS 3.3.  I've
> managed to get some of the blocks lined up enough to compare
> part of VDOS with DOS 3.3 and am able to see that VDOS is
> a substantial re-write of DOS 3.3.

If anyone else would like a copy to play with, let me know.

Regards

Sean

------------------------------------------------------------------------
Sean McNamara                               mailto:sean@macassist.com.au
MacAssist                                             Ph: (02) 8920 0866
Authorised Apple Solutions Reseller                  Fax: (02) 8920 0877
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